ABC’s six-episode run of “The Chair” will bump “Dharma & Greg” and “Spin City” off the air until late February. It’ll mark the first time the Alphabet web will be without comedies on Tuesdays since 1971, when “Happy Days” premiered.

Fox has provided only sketchy details about the content of “The Chamber,” but ABC insiders believe it borrows several key elements from “The Chair.”

ABC’s quizzer, from Touchdown Prods., straps contestants into a chair and monitors their heart rate as they answer questions and face various surprises. Players whose hearts beat too fast begin to lose money.

“The Chamber” also puts players in an enclosed environment, throws different challenges at them and monitors certain body functions.

Execs at Touchdown are so convinced “Chamber” is a clone, they’ve sued Fox and producer Dick Clark for copyright infringement (Daily Variety, Jan. 3.) Fox insiders have said “Chamber” is a distinct program from “The Chair.”

Alphabet began promoting the premiere date during Wednesday’s “American Music Awards,” which coincidentally is produced by Clark. Its late skedding of “The Chair” means ABC will miss out on proper listings in weekly TV publications, though daily papers will get the sked change in time.

Meanwhile, Fox Wednesday confirmed that it will not order any new episodes of frosh laffer “The Tick.” Despite stellar reviews, the skein never generated solid ratings in its Thursday slot.

The final seg will air Jan. 24. No word yet on a replacement, though there’s been speculation Fox could move sudser “Pasadena” to Thursdays.